Field
Embodiments of the disclosure relate generally to current return networks for aircraft lightning and system fault current protection and more particularly to a current return system employing integrated conductive elements in carbon fiber rein forced plastic (CFRP) structural elements.
Background
Large aircraft employ numerous electrical system dispersed throughout the structure. Additionally, aircraft may be subjected to lightning strikes during flight. A current return network (CRN) within the aircraft is required to appropriately direct system fault currents from dispersed electrical systems or currents induced due to lightning strikes. Prior art aircraft with metallic structures provided readily available conductive elements in the structure itself for such current return requirements. Modern aircraft construction with primarily composite materials including the major structural elements of the aircraft require alternative current return systems since the composites typically do not have suitable conductivity. Prior art CRN systems for composite structures, such as U.S. Pat. No. 8,031,458 B2 entitled Current return network published on Oct. 4, 2011, employ dedicated conductive cables routed through the composite structure. These dedicated CRN components may add 750 lbs or more in structural weight to an aircraft with 150 lbs or more in the wing alone. Lightning protection systems (LPS) for aircraft with composite structure have been developed with conductive foils integrated into composite skins or conductive appliques engaged on the skins. However, such LPS still require connection to a CRN for proper grounding and current handling capability.